Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

int main(){
	int h,w;
    cin >> h >> w;
	char c[51][51];
	int check[51][51];
	queue<pair<int,int>> que;
    int i,j;
    int ans=0;
    for(i=1;i<h+1;i++)for(j=1;j<w+1;j++){cin >> c[i][j]; check[i][j]=1e9; if(c[i][j]=='#')ans++;}
    for(i=1;i<h+1;i++)c[i][0]='#';
    for(j=1;j<w+1;j++)c[0][j]='#';
	check[1][1]=1;
    que.push(pair<int,int> (1,1));
	while(!que.empty()){
		int x = que.front().first;
		int y = que.front().second;
		int dx[4] = {1,-1,0,0};
		int dy[4] = {0,0,1,-1};
		que.pop();
		for(i=0;i<4;i++){
			if(c[x+dx[i]][y+dy[i]]=='.' && check[x+dx[i]][y+dy[i]]>check[x][y]+1){
				check[x+dx[i]][y+dy[i]]=check[x][y]+1;
				que.push(pair<int,int> (x+dx[i],y+dy[i]));
			}
		}
	}
    if(check[h][w]==1e9)cout << -1 << endl;
    else cout << h*w-check[h][w]-ans << endl;
}